'Thyroid support' supplements called ineffective, risky

January 1, 2012

Non-prescription "thyroid support" dietary supplements commonly used for weight loss and fighting fatigue are mostly ineffective and may pose a health threat, a new study warns.

"Many people who think they have an underactive thyroid are frustrated because they've been told their TSH (thyroid stimulating hormone) count is normal. If, in light of their symptoms, they strongly disagree, they could ask their practitioner to go beyond the TSH count and test for T3 and something called reverse T3."If the additional, specialized tests show a need, patients have three (prescription-medicine) choices. If tests are normal, it's unlikely the dietary supplements would help. There's probably something else going on."Chandler physician Scott Rigden, a specialist in weight management and author of "The Ultimate Metabolism Diet: Eat Right for Your Metabolic Type." "Nine times out of 10, patients are harming themselves more than helping. I have patients tell me they feel better when they take three times the dose that their doctor tells them to take."I say, 'You may feel better, but unfortunately you're doing a lot of damage to your body. What you don't feel is the heart toxicity and the bone loss leading to osteoporosis.'"Pharmacist Dawn Knudsen-Gerber, professor in the college of pharmacy at Midwestern University in Glendale.The supplements contain widely varying amounts of two kinds of thyroid hormones -- triiodothyronine (T3) and thyroxine (T4) -- apparently derived largely from chopped up animal thyroid glands, according to senior investigator Victor Bernet, an endocrinologist at Mayo Clinic in Florida. The two hormones are regulated by the U.S. Food and Drug Administration and intended for use only in prescription drugs because they can cause serious health problems, including heart irregularities, nervousness and diarrhea, he said.Pharmacist Dawn Knudsen-Gerber, a professor at Midwestern University in Glendale, said other ingredients in some of the products also may be risky. These include the herbs guggul, which can interfere with prescription thyroid medicine, and ashwagandha, which has been insufficiently tested for safety, she said."Selenium (a mineral in some thyroid supplements) probably is of the most concern," Knudsen-Gerber said, "because it does affect thyroid function and it can increase the risk of developing type 2 diabetes."Physician Scott Rigden of Chandler said supplements with such ingredients are far less effective than any of the three prescription medicines he recommends for patients as needed: traditional synthetic thyroid, natural thyroid or a bio-identical thyroid hormone replacement from a compounding pharmacy."The thyroid support supplements look appealing to people who go online because they contain the building blocks needed for the gland to manufacture hormones," Rigden said. "But we are not usually in such a nutritionally deficient state in this country."Bernet and his research team analyzed 10 commercially available thyroid supplements. Of the nine with T3, five would deliver 50 percent or more of the total T3 produced by the body daily. Four of the supplements contained T4, some with a dose that could be double an adult's daily requirement. Bernet, who presented findings at the fall meeting of the American Thyroid Association, said that the supplements are ineffective for most people."The amount of thyroid hormone a normal person would have to take to lose weight would be dangerously high," he said.